This invention relates to a miniaturized, programmable X-ray treatment system having an X-ray source comprised of an electron beam source and an X-ray emitting probe for use in delivering substantially constant or intermittent levels of X-rays to a specified region and, more particularly, to an X-ray source interlock which serves as an interface between the X-ray source and one of a variety of peripheral devices.
In the field of medicine, radiation is used for diagnostic, therapeutic and palliative treatment of patients. The conventional medical radiation sources used for these treatments include large fixed position machines as well as small, transportable radiation generating probes. The current state of the art X-ray treatment systems utilize computers to generate complex treatment plans for treating complex geometric volumes. In most instances, these X-ray treatment systems are controlled using a control console, which provides the operator with an array of pertinent devices by which to operate, test, and calibrate the system, for example.
Typically, these systems apply doses of radiation in order to inhibit the growth of new tissue because it is known that radiation affects dividing cells more than the mature cells found in non-growing tissue. Thus, the regrowth of cancerous tissue in the site of an excised tumor can be treated with radiation to prevent the recurrence of cancer. Alternatively, radiation can be applied to other areas of the body to inhibit tissue growth, for example the growth of new blood vessels inside the eye that can cause macular degeneration.
One type of X-ray treatment system used for such applications is disclosed in U.S. Pat. No. 5,153,900 ('900 patent) issued to Nomikos et al., owned by the assignee of the present application, which is hereby incorporated by reference. The system disclosed in the '900 patent uses a point source of radiation proximate to or within the volume to be radiated. This type of treatment is referred to as brachytherapy. One advantage of brachytherapy is that the radiation is applied primarily to treat a predefined tissue volume, without significantly affecting the tissue in adjacent volumes.
An X-ray source of a typical X-ray treatment system is shown in FIG. 1. The X-ray source 10 includes an e-beam source 12 and a miniaturized insertable probe assembly 14 capable of producing low power radiation in predefined dose geometries or profiles disposed about a predetermined location. The probe assembly 14 includes a shoulder 16 which provides a rigid surface by which the X-ray source 10 may be secured to another element, such as a stereotactic frame used in the treatment of brain tumors. The probe assembly 14 also includes an X-ray emitting tube 18, or "probe", rigidly secured to shoulder 16. A typical probe of this type is about 10-16 cm in length and has an inner diameter of about 2 mm and an outer diameter of about 3 mm.
Typical radiation therapy treatment involves positioning the insertable probe 18 into the tumor or the site where the tumor or a portion of the tumor was removed to treat the tissue adjacent to the site with a "local boost" of radiation. In order to facilitate controlled treatment of the site, it is desirable to support the tissue portions to be treated at a predefined distance from the radiation source. Alternatively, where the treatment involves the treatment of surface tissue or the surface of an organ, it is desirable to control the shape of the surface as well as the shape of the radiation field applied to the surface.
In addition to the need to secure the X-ray treatment system or source to a peripheral device for patient treatments, e.g., a stereotactic frame 20 shown in FIG. 2, there is also a need to combine the X-ray source with other peripheral devices. For example, other peripheral devices may include a variety of apparatus for evaluating the system's performance and calibrating the probe. With each peripheral device, it is paramount for safety reasons that is the operator know whether the device shields the X-ray source and whether it is desirable for the probe to radiate, given the shielding of the peripheral device. Generally, peripheral devices may be divided into three classes. The first class includes devices which are unshielded and no radiation is permitted, for example, devices which measure and/or adjust dimensional features of a probe. The second class includes devices which are fully shielded and radiation is permitted, for example, "water tanks" used in simulating operational environments to accomplish testing of the radiation characteristics and calibrating of a probe. Finally, the third class includes devices which are unshielded and radiation is permitted, for example a stereotactic frame which supports the probe during patient treatment. A problem with typical X-ray sources and classes of peripheral devices is that the probe of the X-ray source may be mistakenly or accidently allowed to radiate with a given peripheral device, causing a radiation hazard to those present.
It is an object of the present invention to provide an X-ray source interlock kit which includes an X-ray source and an interlock assembly, wherein the X-ray source and interlock assembly communicate to control the output radiation of the X-ray source probe for a given class of peripheral device.
It is a further object of the present invention to provide an X-ray interlock as a communicative interface between an X-ray source and a given class of peripheral device, wherein a portion of the interlock is coded with the certain peripheral device characteristics to ensure appropriate output of radiation by the X-ray source probe.